Semi-automatic prober

ABSTRACT

A wafer probe station system for reliability testing of a semiconductor wafer. The wafer probe station is capable of interfacing with interchangeable modules for testing of semiconductor wafers. The wafer probe station can be used with different interchangeable modules for wafer testing. Modules, such as probe card positioners and air-cooled rail systems, for example, can be mounted or docked to the probe station. The wafer probe station is also provided with a front loading mechanism having a rotatable arm that rotates at least partially out of the probe station chamber for wafer loading.

RELATED APPLICATIONS

This application claims the benefit of co-pending U.S. ProvisionalPatent Application No. 62/096,693, filed Dec. 24, 2014, entitled“SEMI-AUTOMATIC PROBER.” The foregoing provisional application is herebyincorporated herein by reference in its entirety for all purposes.

BACKGROUND

The present invention relates generally to semiconductor wafer testing.More particularly, the present invention relates to semi-automaticsystems for testing of electrical devices on silicon wafers.

Semiconductor reliability tests, which are known as wafer levelreliability (WLR) tests, are typically carried out by wafer probers atambient temperatures as high as 350° C. For electrical testing ofsemiconductor wafers, a set of probes on a probe card are typically heldin place while the semiconductor wafer (mounted on a chuck) is movedinto electrical contact with the probe card. The wafer can bevacuum-mounted on a heated chuck. After a die (or array of dice) havebeen electrically tested, the prober then moves the wafer to the nextdie (or array) for the next test to begin. The wafer prober usually alsoloads and unloads the wafers from their carrier (or cassette). A waferprober can also have automatic pattern recognition optics capable ofaligning the contact pads on the wafer with the tips of the probes.

The positional accuracy and repeatability of the wafer chuck movement isvital for making good wafer contact possible. Contact pad sizes inwafers are also getting smaller, so positional accuracy is veryimportant. A wafer probe station that can determine positional accuracyas well as provide versatility and convenience is therefore desirable.

SUMMARY OF THE INVENTION

In accordance with an embodiment, a wafer probe station is provided. Thewafer probe station includes an interface capable of accepting a moduleselected from a plurality of different interchangeable modules. Eachmodule is configured for interfacing at least one probe card with awafer, and a module can be swapped for a different module.

In accordance with another embodiment, a front loading wafer probestation having a chamber is provided. The probe station includes apivoting arm and two wafer supporting segments. Each wafer supportingsegment is rotatably mounted on the pivoting arm, and the wafersupporting segments are movable between a position inside the chamberand a position at least partially outside the chamber.

In accordance with yet another embodiment, a method is provided forloading a wafer into a wafer probe station. The wafer probe station isprovided. The wafer probe station has a wafer loading mechanism housedwithin a chamber. The wafer loading mechanism includes a pivoting armand two wafer supporting segments. Each wafer supporting segment isrotatably mounted on the pivoting arm, and the wafer supporting segmentsare movable between a position inside the chamber and a position atleast partially outside the chamber. The chuck is moved from a testposition to a loading position. The test position and the loadingposition are within the chamber. The pivoting arm is rotated to move thewafer supporting segments at least partially outside the chamber. Thewafer is then loaded onto the wafer supporting segments. The pivotingarm is rotated to move the wafer supporting segments and the wafer backinto the chamber, and the wafer is loaded onto the chuck from the wafersupporting segments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with further objects and advantages thereof, maybest be understood by reference to the following description taken inconjunction with the accompanying drawings in which:

FIG. 1A is a perspective view of an embodiment of a semi-automatic waferprobe station.

FIG. 1B is a perspective view of an embodiment of a semi-automatic waferprobe station having a microscope assembly.

FIG. 1C is a perspective view of an embodiment of a semi-automatic waferprobe station having a microscope assembly and a light tight enclosure.

FIG. 2A is a perspective view of an embodiment of a semi-automatic waferprobe station having a probe positioner module docked to its mountingplate.

FIG. 2B is an exploded perspective view of the embodiment of thesemi-automatic wafer probe station shown in FIG. 2A.

FIG. 2C is a top view of the embodiment of the semi-automatic waferprobe station shown in FIGS. 2A and 2B.

FIG. 2D is a side view of the embodiment of the semi-automatic waferprobe station shown in FIGS. 2A-2C with a microscope assembly.

FIG. 2E is a side view of a probe positioner in accordance with anembodiment.

FIG. 2F is a front view of a probe head in accordance with anembodiment.

FIG. 2G is a top view of the probe positioner shown in FIG. 2E.

FIG. 2H is a top view of a 8× probe positioner in accordance with anembodiment.

FIG. 2I is a top view of a 8× probe positioner in accordance withanother embodiment having longer arms.

FIG. 3A is a perspective view of an embodiment of a probe card.

FIG. 3B is a perspective view of the embodiment of the probe card shownin FIG. 3A further illustrating metal traces that electricallyinterconnect probe tips to electrical contacts on the other end of theprinted circuit board.

FIG. 3C is a side view of the probe card shown in FIGS. 3A and 3B.

FIG. 4A is a perspective view of an embodiment of a semi-automatic waferprobe station having an air-cooled rail system module docked to itsmounting plate.

FIG. 4B is an exploded perspective view of the embodiment of thesemi-automatic wafer probe station shown in FIG. 4A.

FIG. 4C is a top view of the embodiment of the semi-automatic waferprobe station shown in FIGS. 4A and 4B.

FIG. 4D is a side view of the embodiment of the semi-automatic waferprobe station shown in FIGS. 4A-4C with a microscope assembly.

FIG. 5A is is a perspective view of a support rail that supports avertical probe card.

FIG. 5B is a section view of the support rail shown in FIG. 5A.

FIG. 5C is another perspective view of the rail supporting three probeheads.

FIGS. 6A-6D show the movement of a wafer loading mechanism in anembodiment of a wafer probe station.

FIG. 6E is a perspective view of an embodiment of the wafer loadingmechanism.

FIG. 7 is a flow chart of a method 700 for achieving accurate landingson a wafer at a temperature up to about 300 C in a wafer probe station.

FIG. 8 an example of a NIST traceable reference glass, used inaccordance with an embodiment.

FIG. 9 is a flow chart of a method of calculating offset for a givenpoint within the wafer area, based on measured values 1, 2 and 3, inaccordance with an embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

The present invention relates generally to a system for reliabilitytesting of a semiconductor wafer. The embodiments herein describe asemi-automated probe station or prober for testing semiconductor wafers.

Embodiments of a semi-automated probe station described herein arecapable of testing tens to hundreds of devices under test (DUTs)simultaneously. The probe station can include an anti-vibration table,light tight enclosure, digital camera with high powered optics, vacuumhot chuck, multiple-pin mini-probe cards. With the probe stationsdescribed herein, multiple probe cards can be positioned across thesurface of a wafer.

As described in more detain herein, embodiments of a wafer probe stationcan be used with different modules for wafer testing. Modules, such asprobe card positioners and air-cooled rail systems, for example, can beinterchangeable.

As shown in FIG. 1A, according to an embodiment, a probe station 1000can be provided with a mounting plate 1010 on which interchangeablemodules can be docked or mounted to provide a user multiple ways ofinterfacing with a test wafer. The test wafer can be loaded into theprobe station chamber and positioned on a chuck 1015, which can beheated, for testing. FIG. 1B shows the probe station 1000 with amicroscope assembly 1018, which can be used with the probe station 1000.The microscope assembly 1018 is mounted on support rails 1016. In anembodiment, the support rails 1016 also serve as a frame for a lighttight enclosure 1017, which can include multiple retractable panels toform the light tight enclosure 1017 with the frame 1016.

The interchangeable modules that can be mounted on the mounting plate1010 of the probe station individual probe positioners 1020 (e.g.,single pin probe positioners, vertical probe card positioners, or othertypes of probe positioners), as shown in FIG. 1. Other types of modulesthat can be mounted on the mounting plate 1010 include, but are notlimited to, rail systems 1030, traditional 4.5″ cards, 6.5″ cards,various diameter round cards, and custom interfaces for high frequency,high voltage, purged gas, or other custom solutions.

According to the embodiment shown in FIGS. 2A-2D, a probe positionermodule 1020 is mounted to a platen 1022, which is docked or mounted tothe mounting plate 1010 of the probe station 1000. The platen 1022 andthe mounting plate 1010 of the probe station 1000 have common size andmounting hole patterns to allow a user to quickly swap modules asneeded. The interchangeable modules can be provided with handles forease in lifting and positioning of the modules. Modules not in use canbe removed from the probe station 1000 and stored as needed. In theillustrated embodiment, the probe positioner 1020 module is bolted inplace using cap screws and alignment pins in the common mounting holesof the mounting plate 1010 and the platen 1022. According to otherembodiments, cam action latches are provided to allow for simpleswapping of modules. Three points of adjustment can be included on theprobe station 1000 to allow for planarization and calibration of eachmodule when the module is mounted on the mounting plate 1010.

In an embodiment, as illustrated in FIGS. 2A-2D, the module mounted onthe probe station 1000 includes two single XYZT (3-axis lineartranslation, and rotational movement about the Z axis when considered instandard Cartesian coordinates) probe positioners 1020, which aremounted on the mounting plate 1010 of the probe station 1000. Thepositioner 1020 can have either a magnetic or vacuum held base stagebase 1024 for mounting to the probe station 1000.

The XYZT positioners 1020 are designed to accurately position probecards, including standard probe cards as well as vertical probe cards,on the probe station 1000 to contact a wafer. As noted above, the XYZTpositioners 1020 and the platen 1022 can be mounted on the mountingplate 1010 using any suitable fastener, including bolts, clips, latches,etc. FIG. 2E shows an embodiment of an XYZT positioner 1020. In theillustrated embodiment, the XYZT positioner has a stage base 1024 formounting to the probe station 1000. The probe card 10 is typicallymounted on a probe head 25, as shown in FIG. 2F.

According to an embodiment, the XYZT positioner 1020 can be mounted inany orientation on the mounting plate 1010 of the probe station 1000,and in various configurations as shown. In the illustrated embodiments,as shown in FIGS, 2E-21, the XYZT probe positioner 1020 has an adaptorarm 1028 mounted with a vertical probe card 10. As shown in FIGS. 2H and21, the adaptor arms 1028 can have different lengths in differentembodiments. The vertical probe card 10 can be mounted in variousorientations at the end of the adaptor arm 1028, to allow for matchingthe wafer pad orientation as needed. A flex cable routes up the probehead 25, and terminates on a customer interface panel with specificlayouts for a given combination of test equipment, and number of heads.The flex cable the probe card 10 to external test apparatus.

The number and position of the probe heads 25 is largely determined bythe spacing and orientation of the wafer die to be tested. Examples ofpositioners 1020 are shown in FIGS. 2H and 21. Each of the embodimentsshown in FIGS. 2H and 21 has eight probe heads 25. The embodiment of thepositioner 1020 shown in

FIG. 2I has longer adaptor arms 1028 than the embodiment shown in FIG.2H. It will be understood that a positioner can have more or fewer probeheads, depending on other factors, including the size of the positioneras well as the size of the probe heads.

In one embodiment, the XYZT positioner 1020 has a modular adaptor armwith a probe head 25 mounted at one end for aligning and registering avertical probe card 10, such as the vertical probe card available fromQualiTau, Inc. of Mountain View, Calif., for use in testing of deviceson the probe station 1000. An embodiment of a vertical probe card 10 isdescribed below and with reference to FIGS. 3A-3C. Major problems arisefrom heating of a typical horizontal probe card and probe head system. Ahorizontal probe card is the closest component to the hot chuck thatholds the wafer and can suffer a drastic degradation in performance dueto temperature dependent leakage current. The large exposed area of thehorizontal probe card exacerbates the degradation in probe performanceSince device testing can take place at temperatures up to 300° C.,vertical probe cards are useful for testing semiconductor devices atelevated temperatures, as the vertical probe cards keep the electricalsignals above and away from a hot chuck.

FIG. 3A is a perspective view of an embodiment of a vertical probe card10 and includes a printed circuit board 12 with a plurality of slots 14therethrough for facilitating the flow of cool air. At one end of theprinted circuit board 12 is a tip assembly including a plurality ofmetal probe tips 16 in a ceramic support 18 and on an opposing end ofprinted circuit board 12 is an electrical connector and fastener 20which is used for physically supporting the probe card in a test systemand connects the probe tips 16 to a flexible (flex) cable.

FIG. 3B further illustrates printed circuit board 12 and metal traces 22which electrically interconnect the probe tips 16 to electrical contacts24 on the opposing end of board 12. The electrically conductive patternof metal traces or discrete wires 22 interconnect individual probe tipsto one of the contacts 24. As illustrated, ceramic support 18 with probetips 16 supported therein is attached to board 12 by means of screwfasteners 26.

FIG. 3C is a side view of the probe card illustrating electricalconnector and fastener 20 which engages a receptacle in supportapparatus to hold probe card 10 in a generally vertical or perpendicularposition with respect to a wafer undergoing test. Only the ends of tips16 engage the device undergoing test, thereby limiting heat conductiveflow through the probe tips. The vertical alignment of probe card 10limits the exposure of the card to heat emitted by the heated devicechuck. Moreover, convective flow of air from the heated chuck to theprobe card and supporting apparatus is disrupted by flow of cool airprovided by the support assembly, as described below. The probe card 10is typically mounted on a probe head 25, as shown in FIG. 2F.

Reliability testing of semiconductor devices can demand very differentand specific equipment for each type of device or testing methodologyused. As discussed above, the probe station 1000 addresses the specificneeds of each type of device and/or testing methodology by allowingusers to use the probe station 1000 to interface with multiple stylesand configurations of probe pins, cards, or other contact methods.According to embodiments described herein, a probe station 1000 providesa system for interfacing with different interchangeable modules.

The modular aspect of the probe station 1000 allows the user to easilyremove and replace one module with another, depending on the type ofwafer testing desired. Custom PCB and connector assemblies are alsodesigned to be interchangeable, depending on the type of equipment beingimplemented for electrical testing. These assemblies are designed withinputs for triax cables, discrete wiring, coaxial, and other specificcable and connector standards.

To add to the flexibility of step and repeat testing of silicon wafersfor reliability analysis, the removable probe positioner 1020 shown inFIG. 2 can be replaced with a different modular assembly. For example,FIGS. 4A-4D show an embodiment of a removable array of air-cooled rails1030, such as those available from Qualitau, Inc., mounted on themounting plate 1010 of the probe station 1000.

As shown in FIGS. 4A-4D, an air-cooled rail assembly 1030 can be mountedon the mounting plate 1010 of the semi-automated probe station 1000 asan interchangeable module. The rail assembly 1030 allows testing ofmultiple die, which is important to increase yield in testing over time,as well as to ensure the appropriate sample size for a given set of testconditions.

The air-cooled rail assembly 1030 and the mounting plate 1010 of theprobe station 1000 have common size and mounting hole patterns to allowa user to quickly swap modules as needed. The rail assembly 1030 can beprovided with handles for ease in lifting and positioning. In theillustrated embodiment, the rail assembly 1030 module is bolted in placeusing cap screws and alignment pins in the common mounting holes of themounting plate 1010 and the rail assembly 1030. According to otherembodiments, cam action latches are provided to allow for simpleswapping of modules.

The rail assembly 1030 includes an array of multiple air-cooled supportrails 30 for supporting vertical probe cards 10. FIG. 5A is aperspective view of a support rail 30 that supports a vertical probecard 10 and a probe head shown generally at 32 above a device undergoingtest (wafer) and a heated support chuck. In an embodiment, the probehead 32 can be adjusted manually along three axes of movement by meansof control knobs 34, 36, 38. According to another embodiment, a userinterface can adjust the probe head 32 semi-automatically. A flex cable40 is supported on the top of rail 30 and interconnects probe card 10 toexternal test apparatus. It should be noted that the flex cable 40 candegrade in performance if overheated.

FIG. 5B is a section view of rail 30 which includes internal channels42, 44 for the flow of air used for cooling probe head 32, probe card10, and flex cable 40. Air from the internal channels is emitted throughopenings in rail 30 with the air being directed through probe head 32and probe card 10 for disrupting convective hot air flow from the heatedchuck which holds the device under test. Accordingly, overheating offlex cable 40 and the printed circuit board of test probe 10 can beavoided. In this embodiment is will be noted that channel 30 includes amember 48 having dovetail flanges which engage mating dovetail flangesof probe head 32 as shown generally at 50.

FIG. 5C is another perspective view of the rail 30 supporting threeprobe heads 32. In this embodiment, only one probe card 10 is shown onthe probe heads to further illustrate openings or slots for facilitatingthe flow of cool air from openings 54 in frame 30 through the probeheads 32 and through the openings 14 in probe card 10. It will be notedin this embodiment that each probe head 32 has a lever mechanism showngenerally at 56 which can be used for locking a probe head in thedovetailed flanges 50 of rail 30.

Some probe station systems load wafers from the side using a cassette.Most conventional probe station systems that load a wafer from the frontrequire the entire chuck assembly to be removed from the probe station.Removing the chuck assembly has a few drawbacks, including: (i) reducedmechanical stability of the chuck mechanism; (ii) increased complexityof the stage system, and (iii) significant temperature shift if thechuck is soaked at a specific elevated temperature.

An embodiment of the probe station 1000 provides a simple and elegantsolution to this problem by using a 2-piece pivot arm 1100 that canrotate out of the front of the probe station 1000 to accept a wafer1200, transport the wafer 1200 to a chuck surface, and then “open” thetwo wafer holding segments 1150 to retract out of the way while stillenclosed within the probe station 1000. This front-loading feature for asingle wafer 1200 allows a user to easily load the wafer 1200 from thefront without causing a temperature shift for the chuck 1015, as thechuck 1015 remains within the probe station chamber 1060.

As shown in the illustrated embodiments, the probe station 1000 can beprovided with a drop down front wafer loading door 1050 for covering andexposing an opening in its front face for loading and unloading wafers.In other embodiments, the door can have a different configuration, suchas a sliding door or a side-swinging door. To facilitate easy singlewafer loading, the probe station 1000 has an internally housed arm thatcan be rotated outwards to retrieve and deliver a wafer 1200 to thehot-chuck 1015.

A front loading mechanism for wafers is described with reference toFIGS. 6A-6E. FIG. 6E shows the interior chamber 1060 of the probestation 1000 as seen from the opening in the front face of the probestation 1000. Opening the drop down door 1050 provides access to thefront loading mechanism for wafers 1200, such as 200 or 300 nm wafers.In FIG. 6E, the view is shown from the bottom side to illustrate theloading mechanism, which includes a pivot arm 1100 and two wafersupporting segments 1150, supporting a wafer 1200. In the embodimentshown in FIG. 6E, the two wafer supporting segments 1150 rotate aboutone end of the pivot arm 1100. The other end of the pivot arm 1100rotates about a pivot point attached to a platform of the probe station1000.

FIGS. 6A-6D show the wafer loading process in accordance with anembodiment. As shown in FIG. 6A, the chuck 1015 and the loadingmechanism (pivot arm 1100 and two wafer supporting segments 1150) are inthe housed position, which is also the testing position. The housed ortesting position is the position in which the chuck 1015 and the loadingmechanism are stored when not in use and when a wafer 1200 is supportedby the chuck 1015 and being tested. As shown in FIG. 6A. the two wafersupporting segments 1150 are rotated away from one another and out ofthe way of the chuck 1015.

When a wafer 1200 is to be loaded, the user prompts the probe station1000 system. When prompted via software, the chuck 1015 will move alongthe X, Y and Z axes from the test position to the loading position. Asshown in FIG. 6B, the chuck 1015 moves toward the wafer supportingsegments 1150 and the door 1050 into a loading position. According to anembodiment, the chuck 1015 also moves downward as it moves toward thewafer supporting segments 1150 and door 1050.

The door 1050 then opens and the two wafer supporting segments 1150rotate toward one another and the pivot arm 1100 rotates the two wafersupporting segments 1150 forward out of the door opening so that a wafer1200 can be loaded onto the wafer supporting segments 1150. As shown inFIG. 6C, the wafer 1200 can be placed onto the wafer supporting segments1150 in this position. It will be understood that the chuck 1015 is notshown in FIG. 6C for simplicity and that the chuck 1015 is actually inthe loading position within the chamber 1060 to which it was moved asshown in FIG. 6B.

As shown in FIG. 6D, the pivot arm 1100 rotates the two wafer supportingsegments 1150 and the supported wafer 1200 back into the chamber 1060where the wafer 1200 can be placed onto the chuck 1015 in the loadingposition. The wafer supporting augments 1150 then rotate independentlyout of the way (back to the housed position), within the probe stationchamber 1060. The chuck 1015, while supporting the wafer 1200, thenrotates back to the testing position where the wafer 1200 can be testedusing an interchangeable module (e.g., probe positioner, rail system,etc.), as described above.

With a traditional probe card setup on a semi-auto prober, users aregenerally limited to a single site, or a fixed number of sites withlimited adjustment. An embodiment of the semi-automated probe station1000 can handle up to 16 individually adjusted probe heads at atemperature as high as about 300° C., to allow for easy adjustment of asingle site within the probe head array. This allows the user tocustomize the pattern, spacing, and number of heads being landed andused for testing. This also allows for repositioning of a single head(or more) if the device within the array is dead. The combination of theadjustable rail and head array, with the functionality of an automatedXYZT stage provides a solution to maximize flexibility.

In order to accurately step and repeat landings with a wafer probingsystem, the user needs to have accurate information regarding the sizeof landing pads and the pitch between repeating die for testing. Thiscan be problematic when either this information is unknown, or thesevalues change due to thermal expansion of the silicon wafer itself. Forexample, 300 mm silicon wafers can expand in size significantly whenelevated to 300° C., and the die pitch can become as much as 25 μmlarger than at room temperature. In order to correct for thisdifference, an embodiment of the probe station 1000 utilizes an imageprocessing and pattern recognition routine to detect and measure thespacing of die for each set temperature to offset this expansion andensure accurate landings at any temperature.

FIG. 7 is a flow chart of a method 700 for achieving accurate landingson a wafer at a temperature up to about 300 C in a wafer probe station.According to this method 700, a database is generated, saved, andreferenced by software to accurately compensate for the temperatureoffset from room temperature values. Pad size and other features canalso be measured automatically, using image processing from the CCD andpattern recognition. In step 710, a database is generated by detectingand measuring spacing of a die at each predetermined temperature andsaving the measured spacing for each predetermined temperature. In step720, the spacing of a die on the wafer is detected and measured. In step730, the temperature of the wafer is measured. In step 740, the databaseis referenced the determine the amount of offset due to temperaturechange,

Overall, the positional accuracy and repeatability of the wafer chuckmovement is vital for making good wafer contact possible. Good wafercontact is a factor of repeatable and appropriate scrub mark. “Scrubmark” is the trench and hillock formed on an exposed metal pad on thewafer surface when a downward force is applied from the probe needles.These scrub marks need to be on target, without the pins making contactwith surrounding layers of passivation materials that can contaminatethe pins, and skew electrical measurements from their true values. Withpad sizes shrinking to as small as 30 μm×30 μm, and probe pinsincreasing in quantity per site, as well as pad to pad pitch, having aprober system accurate enough to ensure this landing is vital. Anembodiment of the probe station 1000 employs a custom method ofmulti-point XY position calibration and correction.

With reference to FIGS. 8 and 9, a method 900 of calculating offset fora given point within the wafer area, based on measured values 1, 2 and 3will be described. The method employs a National Institute of StandardsTesting (NIST) traceable reference glass, as shown in FIG. 8, which usesa grid of lines that can be recognized by a special software routine,and an image processing and pattern recognition software library. Usingthis method 900, information can be gathered for thousands of datapoints on the wafer, with regard to the offset. The offset is thedifference between where the system thinks the wafer is, and where thewafer has actually moved. These values are then stored in a file to bereferenced by the controller software, to then correct for thesemeasured and known inaccuracies in position. According to the method900, a NIST traceable reference glass mask grid is provided in step 910.In step 920, information for data points on the wafer is gathered todetermine an offset due to temperature change or chuck movement. Theoffset is the difference between where the contact pad is supposed to beand where it actually has moved due to temperature change or chuckmovement. In step 930, X and Y coordinates on the glass mask grid arecalibrated by correcting for the offset determined in step 920. Thecalibration is performed to determine an accurate location for a contactpad.

Although only a few embodiments of the invention have been described indetail, it should be appreciated that the invention may be implementedin many other forms without departing from the scope of the invention.It should be apparent that the described wafer temperature measurementtool can be used in a wide variety of applications. In view of all ofthe foregoing, it should be apparent that the present embodiments areillustrative and not restrictive and the invention is not limited to thedetails given herein, but may be modified within the scope andequivalents of the appended claims.

What is claimed is:
 1. A wafer probe station, comprising an interfacecapable of accepting a module selected from a plurality of differentinterchangeable modules, wherein each module is configured forinterfacing at least one probe card with a wafer, wherein a module canbe swapped for a different module.
 2. The wafer probe station of claim1, further comprising: a chuck; and a rotating arm comprising a firstsegment and a second segment to support the wafer, wherein the arm isconfigure to rotate and pivot out of an opening in a front surface ofthe wafer probe station to accept the wafer and rotate and pivot intothe wafer probe station to load the wafer to a surface of the chuck,wherein the first segment and the second segment are configured toretract away from the wafer and the chuck after loading the wafer to thesurface of the chuck.
 3. The wafer probe station of claim 1, wherein theplurality of different interchangeable modules comprises a probepositioner configured to align the at least one probe card with thewafer, wherein the probe positioner can move the at least one probe cardlinearly along three X, Y, Z axes as well as rotationally about the Zaxis.
 4. The wafer probe station of claim 3, wherein the probepositioner has an arm for positioning a probe card vertically above thewafer during testing of the wafer.
 5. The wafer probe station of claim3, wherein the positioner is a magnetic or vacuum based positioner. 6.The wafer probe station of claim 1, wherein the plurality of differentinterchangeable modules comprises an air-cooled rail assembly fortesting multiple die on the wafer, wherein the rail assembly canaccommodate a plurality of individually adjustable probe heads.
 7. Thewafer probe station of claim 6, wherein the rail assembly positions theprobe card vertically above the wafer during testing of the wafer. 8.The wafer probe station of claim 1, wherein the plurality of differentinterchangeable modules comprises an adaptor for 4.5″×6″ probe cards. 9.The wafer probe station of claim 1, wherein the wafer probe station iscapable of achieving accurate landings on a wafer at a temperature up toabout 300° C. in the wafer probe station, the wafer probe stationfurther comprising: an image processor for detecting and measuringspacing of a die the wafer; and a database generated by detecting andmeasuring spacing of a die at predetermined temperatures and savingmeasured spacing for each predetermined temperature in the database todetermine an amount of offset for each predetermined temperature. 10.The wafer probe station of claim 1, further comprising a NIST traceablereference glass mask grid, wherein X and Y coordinates on the glass maskgrid are calibrated to determine an accurate location for a contact padto position probe needles on a contact pad on the wafer.
 11. The waferprobe of claim 9, wherein the X and Y coordinates are calibrated bygathering information for data points on the wafer to determine anoffset, wherein the offset is a difference between where the contact padis supposed to be and where it actually has moved due to temperaturechange or chuck movement, and correcting for the offset determined
 12. Afront loading wafer probe station having a chamber, comprising: apivoting arm; and two wafer supporting segments, wherein each wafersupporting segment is rotatably mounted on the pivoting arm, wherein thewafer supporting segments are movable between a position inside thechamber and a position at least partially outside the chamber.
 13. Thefront loading wafer probe station of claim 12, further comprising achuck movable between a test position and a loading position.
 14. Thefront loading wafer probe station of claim 13, wherein the test positionand the loading position are within the chamber.
 15. The front loadingwafer probe station of claim 12, wherein the wafer supporting segmentsare movable to a position at least partially out of an opening in afront face of the wafer probe station.
 16. The front loading wafer probestation of claim 15, further comprising a door that opens to expose theopening in the front face of the wafer probe station.
 17. A method ofloading a wafer into a wafer probe station, the method comprising:providing the wafer probe station having a wafer loading mechanismhoused within a chamber, the wafer loading mechanism comprising: apivoting arm; and two wafer supporting segments, wherein each wafersupporting segment is rotatably mounted on the pivoting arm, wherein thewafer supporting segments are movable between a position inside thechamber and a position at least partially outside the chamber; moving achuck from a test position to a loading position, wherein the testposition and the loading position are within the chamber; rotating thepivoting arm to move the wafer supporting segments at least partiallyoutside the chamber; loading the wafer onto the wafer supportingsegments; rotating the pivoting arm to move the wafer supportingsegments and the wafer back into the chamber; and loading the wafer ontothe chuck from the wafer supporting segments.
 18. The method of claim17, further comprising moving the chuck from the loading position backto the test position after loading the wafer onto the chuck.
 19. Themethod of claim 17, further comprising rotating the wafer supportingsegments away from each other and away from the chuck after loading thewafer onto the chuck.
 20. The method of claim 17, wherein the chuckmoves along the X, Y, and Z axes.